With Napoleon safely removed from the scene, in distant St Helena, the Bourbon king Louis XVIII - restored to the throne now for the second time - attempts to establish the constitutional monarchy which has been the condition of his dynasty's return.

The pattern is intended to echo the parliamentary system established in Britain, with one chamber made up of peers and another of elected deputies. As with the Cavalier parliament after the English restoration in 1660, the first elections result in an ultra-royalist majority. Vengeance for the recent sufferings of the landed classes is high on the agenda.

The king, personally inclined to moderation, contrives to steer a middle course for a few years after 1816, when new elections return a more centrist parliament. But his task is made more difficult after the assassination, in 1820, of his nephew the duc de Berry.

The event prompts an immediate swing to the right, accentuated because the young man's father - the future Charles X - is already the leader of the ultra-royalist faction in the country. The 1820s see a continuous drift towards reactionary policies, including the unscrupulous revision of the franchise to favour the rich. The process accelerates after Charles X succeeds his brother in 1824.

At the very start of his reign Charles X makes a dramatic statement of his intended policy. He has himself crowned in the cathedral at Reims. The Holy Ampulla, believed to have been brought from heaven by the Holy Ghost, has been smashed by a republican in 1793. But Charles is relieved to discover that faithful royalists have rescued the few drops of the sacred liquid needed for his anointment. The ceremony can be carried out with full medieval pomp.

Appropriate political measures follow. Power is returned to the clergy. The Jesuits reappear. Large sums of money are allotted to recompense the aristocracy for lost lands.

Hostility mounts and is even expressed in parliament. Charles responds by selecting increasingly right-wing ministers. Eventually in desperation, on 26 July 1830, he dissolves the elected chamber, severely restricts the freedom of the press, and announces a new electorate limited to 25,000 grandees.

This is too much for the Parisians, always conscious of their revolutionary traditions. Barricades appear once again in the streets. Angry crowds brandish the tricolour, symbol of the revolution but replaced since 1815 by the Bourbon flag. The mood is captured in romantic form in Delacroix's inspirational painting of this same year, Liberty Guiding the People.

After three days of street-fighting (July 27-29), the people win. Charles X, king of pomp and ceremony, flees from the city. In his place there arrives a distant Bourbon cousin, Louis Philippe, the duc d'Orléans. He cuts a very different figure.

When he presents himself on July 31 at the Hôtel de Ville, Louis Philippe is wrapped in a tricolour. In an extraordinary echo of distant events, he is greeted on the steps by Lafayette - a leading player in a similarly dramatic scene in Paris forty-one years earlier, in 1789. On 9 August 1830 Louis Philippe is formally proclaimed 'king of the French ... by the will of the people'. He becomes known, with good reason, as the Citizen King.

The July Monarchy: 1830-1848

The Citizen King finds it hard to govern a nation in which the number of disaffected factions has increased with each change of regime. The extreme left wing, deriving from the Jacobins, has recently found new support in the increasingly industrialized cities. Meanwhile more moderate republicans, also with their roots in the revolution of 1789, hope for a system akin to that of the Directory.

The imperial years have also left a Bonapartist faction, dreaming of a new empire linked with Napoleon's family. Even the royalists, having achieved their main purpose with the Bourbon restoration, are now split into two incompatible groups.

The royalists faithful to the main Bourbon dynasty, describing themselves as the Legitimists, believe that Charles X's grandson (son of the assassinated duc de Berry) should be king as Henry V, with Louis Philippe merely regent. The other royalist faction, backing Louis Philippe, are known as the Orleanists.

Louis Philippe lacks a clear democratic mandate (the franchise in his reign extends only to some 200,000 wealthy citizens), yet he has little of his own to offer - except the first glimpse of a trend which becomes familiar only in the late 20th century. As the bourgeois monarch, he can be seen walking in the streets carrying his own umbrella. Fascinated at first, Parisians soon find this uninspiring.

The result is a reign both unsettled and violent. There are several attempts on Louis Philippe's life (eighteen people are killed and many wounded in 1836, when assassins contrive an 'infernal machine' which can fire twenty-five guns simultaneously at a royal procession). And there are frequent republican uprisings - in Lyons in 1831, in Paris in 1832, in both cities again in 1834.

The predictable response is a clampdown on political liberty. This provides some calmer years at a time of prosperity in the early 1840s. But from 1846 political dissatisfaction coincides with economic setback, with the wheat and potato crops failing in much of Europe.

In 1847 a campaign for constitutional reform is conducted in a series of high-profile banquets. Feeling threatened by this campaign, the government bans a banquet due to be held on 22 February 1848 in Paris. The result is a large demonstration and the reappearance of barricades in the streets (with a new element, the red flag of socialism, now seen in working-class districts).

The usual pattern of escalation occurs. On February 23 troops fire on the demonstrators. The following day Louis Philippe abdicates and withdraws to England. He intends his grandson to succeed him. But the Paris crowd, converging on the Hôtel de Ville, proclaims instead France's second republic.

The Second Republic: 1848-1852

In its first few days the provisional government of the new republic passes several radical measures. It proclaims the right of everyone to work, proposes state-run national workshops to ensure full employment, limits the length of the working week, and introduces universal male suffrage over the age of twenty-one - increasing the electorate at a stroke from 200,000 to some nine million.

Within weeks the national workshops are deemed impractical and are abandoned, being replaced with schemes such as the extension of military conscription. The result is an insurrection in the working-class districts of Paris, in June 1848. It is ruthlessly suppressed by the republican government.

In the light of these events, and of the rash of revolutions elsewhere in Europe this summer, the electorate inclines to an authoritarian figure when the moment is reached, in December 1848, for the choice of the republic's first president. The winner is Louis Napoleon, nephew of the emperor. He receives more than five million votes, nearly four times the score of his nearest rival.

This is a moment for which Louis Napoleon has been working tirelessly, often to tragi-comic effect. At dawn one day in 1836 he has presented himself in Napoleonic uniform to an artillery regiment in Strasbourg, inviting them to join him in restoring his uncle's empire. When they fail to do so, he is inevitably arrested.

On that first occasion the French king, Louis Philippe, thinks it wise to underplay this feeble act of insurrection. Louis Napoleon is quietly deported to the United States. But the would-be emperor is not so easily discouraged. In 1840 he lands near Boulogne with fifty followers and invites the garrison to help him recover his rightful empire. Again he is arrested, but this time he is tried and imprisoned for life. In 1846 he escapes, disguised as a labourer, and makes his way to London.

The election of a president in 1848 at last offers him a legitimate route to power. Even with his somewhat preposterous track record, Louis Napoleon sweeps to victory on the popular vote. Such is the magic of the family name.

The presidency is for a fixed term of four years. Louis Napoleon skilfully builds up support around the country, but he fails to persuade the national assembly to vote a change of law enabling him to continue in office after 1852.

He resolves this dilemma with a brilliantly organized coup d'état. During the night of 1 December 1851 troops enter the assembly in Paris while large numbers of Louis Napoleon's political enemies around the country are arrested. He then uses the Napoleonic device of a plebiscite to seek the nation's approval for a new constitution.

Louis Napoleon is helped by the fact that the assembly, inclining again to royalist sympathies, has in 1850 disenfranchised some three million of France's poorest voters. He restores universal male suffrage in time for the plebiscite on December 20, in which he asks for dictatorial powers as president for a span of ten years. Seven and a half million voters approve of his plans, with less than a tenth of that number registering dissent.

A year later he again follows his uncle's example, enquiring whether the French people would like him to be their emperor. Once more an overwhelming majority say yes. Louis Napoleon takes the title Napoleon III, being supposedly the third ruler in his line. France's Second Empire begins.

The Second Empire at home: 1852-1870

The constitution established by Napoleon III, with the mandate of the plebiscites of 1851 and 1852, enables him to rule with virtually unrestricted personal authority. The members of the upper chamber are appointed. The lower house is elected for six years but sits for only three months in the year; its debates are published in censored form, and the press is under similar restrictions.

After years of weak rule and public disorder, France at first welcomes firm government. The economic cycle is on the upturn. Industrialization is proceeding apace. The network of railways is greatly extended, radiating out from Paris. Financial services are developed. Reduction of tariffs leads to a marked increase in levels of trade.

These signs of prosperity and national energy are reflected in a glittering court life very different form the drab example set by the Citizen King. In 1853 the emperor marries a beautiful Spanish countess, Eugénie de Montijo. The empress becomes the central figure in the glamorous festivities which are the public face of the Second Empire.

Nevertheless by the end of the decade there is mounting dissatisfaction at the moribund political scene masked by this glitter. Napoleon III responds to the challenge with sound political sense. Rulers have traditionally clamped down at the first sign of unrest, but he takes the opposite course. He defuses the situation by becoming more liberal.

An amnesty announced in August 1859 allows the return of many political exiles. In 1860 the elected assembly is given greater powers and the restraints on the press are somewhat eased. The new atmosphere encourages political dissent (in the election of 1863 there are two million opposition votes, and republican candidates do well in the larger cities), yet the emperor does not reverse the direction of his policy.

Further relaxations are decreed in 1867. By the 1869 election the opposition vote has increased to three million. Again the emperor is undeterred. The public's message prompts him to restore genuine parliamentary government.

The leader of the liberal group in the lower chamber, Émile Ollivier, is invited to form a ministry. He and his colleagues devise with the emperor a constitution which is put to the people in 1870 in yet another Napoleonic plebiscite. Once again it passes handsomely, with more than seven million voters expressing their approval.

An imperial dictatorship has been transformed, almost seamlessly, into a constitutional monarchy. The new arrangement is hailed as the 'liberal empire'. But it is destined to have only two months of life. Napoleon III's relative failure in foreign policy has undoubtedly made him more inclined to grant concessions at home. But a final and costly disaster, at the hands of Prussia, proves the last straw.

The Second Empire abroad: 1852-1870

Fascinated by every detail of his illustrious uncle's career, Napoleon III is eager to play a similarly impressive role on the international stage. His first major undertaking achieves all he might wish. By standing up to Russia in 1852 on the issue of the Holy Places in Palestine, he pleases Roman Catholic opinion in France. In the resulting Crimean War, France is on the winning side. And the holding of the peace talks in Paris in 1856 gives the new empire a visibly central role in European affairs.

But this is the last of Napoleon III's foreign policies to turn out exactly as he would wish.

In 1859 he undertakes an adventure in north Italy, the arena which saw many of Napoleon I's greatest successes. His intention is to repeat the earlier Napoleonic achievement of sweeping the Austrians from Italy. To some extent he succeeds in his aim. After a narrow victory at Magenta in June he enters Milan as a liberator (and by agreement brings Savoy and Nice back within French borders). But his sudden treaty with Austria, after the horrors of Solferino, leaves almost everyone dissatisfied.

During much of the 1860s France's main foreign involvement is in Mexico, where the ill-conceived attempt to set up an empire under French patronage ends in utter disaster in 1867.

But Napoleon's downfall comes at the hands of Prussia, the nation so profoundly humiliated by his uncle in 1807.

In 1866 the emperor is wrong-footed by the rapid victory of Prussia over Austria in the Seven Weeks' War. This leaves France with an unexpectedly powerful and uncompromising neighbour on her eastern frontier. War between the two is now perhaps inevitable - though when it does occur, in 1870, the immediate cause is a succession of diplomatic bungles and deceptions.

Franco-Prussian War: 1870-71

Ever since Prussia's rapid success in the Seven Weeks' War of 1866, and the resulting consolidation of Prussian territory on the Rhine, there has been alarm and resentment in France at the growth of this ambitious neighbour. It is dramatically increased in 1870 when news leaks on July 3 that a prince of the Prussian Hohenzollern family has been offered, and has accepted, the vacant throne of Spain.

Having fought so often in the past against being surrounded to south and east by the Habsburg dynasty, there is public outcry in France at the prospect of the same trick now being pulled off by the Hohenzollern. In an escalating crisis, the Prussian king William I withdraws his relation's candidacy on July 12.

The matter might have rested there, but for a diplomatic blunder on the French side. The French ambassador, in an audience with William I at Ems on July 13, demands an assurance (amounting to a slur on the king's good faith) that the candidacy will never be renewed. William refuses to give this assurance. He then sends a telegram to Bismarck describing, in neutral terms, the audience and its outcome.

Bismarck, irritated at the collapse of his Spanish policy, shortens the telegram before publication in such a way as to imply that the Prussian king has treated the French ambassador with disdain. Public opinion in France, already inflamed, now explodes. The French government declares war on Prussia on July 19.

France suffers as rapidly and as conclusively at Prussia's hands as Austria did four years previously. Again the significant period of warfare lasts less than seven weeks. In early encounters near Metz the French almost hold their own against the Prussians, but by August 31 a large French army is surrounded near Sedan.

During September 1 the French cavalry, charging desperately to break out of the encirclement, suffer heavy casualties from the Prussian artillery. On the following day the French surrender. After losses in the battle of 38,000 men (killed, wounded or missing), another 83,000 now lay down their arms and become prisoners of the Germans. Among them is the French emperor himself, Napoleon III.

The events at Sedan bring to an end one empire, in France, and hasten the creation of another, in Germany. But they do not immediately end the war.

When the news of Sedan reaches Paris, a government of national defence is rapidly formed. Its first action, on September 4, is to depose Napoleon III and declare a republic. But there is nothing now to stop the German army on its march towards Paris. The siege begins on September 19. The only chance of relieving the city is to raise new armies in the provinces. And here aeronautics play their first significant role in warfare.

On October 7 a balloon rises from Paris (historic city of the balloon). It floats above the Germany army and lands far beyond their lines. It carries Léon Gambetta, minister of the interior in the new republican government. Two days later he reaches Tours and begins to orchestrate a campaign of guerrilla warfare which severely disrupts the smooth Prussian military operation.

But it can only delay the eventual capitulation. Early in 1871, on January 23, delegates from Paris pass through the German lines to Versailles to agree an armistice. They find the Prussians in an excited mood. Just five days previously, in Louis XIV's famous hall of mirrors in the palace of Versailles, the Prussian king has been proclaimed emperor of a united Germany.